Micromechanical microphone systems usually include a sound transducer device integrated on a MEMS chip for converting sound energy into electrical energy, a first electrode deflectable by sound energy, and a fixed, perforated second electrode (back plate) capacitively cooperating. The deflection of the first electrode is determined by the difference in the sound pressures in front of and behind the first electrode. When the deflection changes, the capacitance of the capacitor formed by the first and second electrodes is changed, which is metrologically detectable. Such a micromechanical microphone system is known from U.S. Pat. App. Pub. No. 2002/0067663.
Due to the fixed, perforated second electrode (back plate), the movement of the diaphragm is limited, and thus the dynamic range of the microphone system is limited, and moreover additional noise is generated by the air flow resistance.
From U.S. Pat. App. Pub. No. 2014/0339657 are known piezoelectric microphone systems, including vibrating beams, which enable a larger dynamic range and prevent additional noise, which increases the overall quality. The fundamental principle of the piezoelectric microphone systems is the use of a piezoelectric material, such as AIN, PZT, or another suitable piezoelectric material, which produces charges upon deformation and accordingly renders a voltage metrologically detectable.
At very high sound pressure levels or with extreme shocks, the vibrating beams of piezoelectric microphone systems bend greatly. In the worst case, this may result in irreparable damage to the vibrating beams.
A piezoelectric system is known from U.S. Pat. App. Pub. No. 2013/0088123, in which the vibrating beams are limited by an upper and a lower stop to an upper and a lower limiting deflection.